Essential vocabulary:

1. motion – движение

2. to provide – обеспечивать, снабжать

3. matter - материал

4. confinement - ограждение

5. density - плотность

6. fan - вентилятор

7. pressure - давление

8. to transmit – транслировать, передавать

9. piston - поршень

10. due to – благодаря чему-либо, из-за

11. friction - трение

12. to remain – оставлять, сохранять

13. velocity - скорость

14. to derive - получать

15. to convert - превращать

16. to enlarge – увеличивать, расширять

17. cross section – поперечное сечение

18. to deliver - доставлять

19. machine tools - станки

20. to increase - увеличивать

21. counterpart – аналог

22. reciprocating - поршневой

23. mining – добыча ископаемых

24. flexibility – гибкость

25. to utilize - использовать

II. Give your own definitions to the following words:

1. application

2. fluid

3. container

4. device

5. control

6. spacecraft

7. century

8. technology

III. Give the English equivalents to the following phrases:

• область науки;

• жидкость под давлением;

• наполнять контейнер;

• важная работа для человека;

• передавать во все направления;

• применение давления;

• устанавливать гидравлическую систему;

• насос увеличивает давление;

• механика жидкостей;

IV. Are these statements true or false? Correct the false ones with the right information:

1. Hydraulics is a branch of science concerned only with the practical applications of gases.

2. The scope of hydraulics extends to such mechanical devices as fans and gas turbines and to pneumatic control systems.

3. French scientist-philosopher Blaise Pascal and Swiss physicist Daniel Bernoulli formulated the laws on which modern computer technologies are based.

4. Pascal's law was formulated in about 1560.

5. Until the 19th century it was not possible to develop velocities and pressures much greater than those provided by nature.

6. In hydraulic-power systems there are three elements: the driver, the pump and the control valves.

7. In the operation and control of machine tools, farm machinery, construction machinery, and mining machinery, fluid power can compete with mechanical and electrical systems.

V. Answer the following questions:

1. What matters does hydraulics deal with?

2. What do you know about Pascal’s law? What is it used for?

3. What does Bernoulli's law state?

4. When were self-contained hydraulic units developed?

5. How many elements are there in hydraulic- power systems? What are they?

6. What motion can produce motors in the load?

7. What force can provide fluid power?

8. Why did hydraulic-power systems become major energy-transmission technologies?

Fluid mechanics

Fluid mechanics is a science concerned with the response of fluids to forces exerted upon them. It is a branch of classical physics with applications of great importance in hydraulic and aeronautical engineering, chemical engineering, meteorology, and zoology.

The most familiar fluid is of course water, and an encyclopedia of the 19th century probably would have dealt with the subject under the separate headings of hydrostatics, the science of water at rest, and hydrodynamics, the science of water in motion. Archimedes founded hydrostatics in about 250 BC when, according to legend, he leapt out of his bath and ran naked through the streets of Syracuse crying “Eureka!”; it has undergone rather little development since. The foundations of hydrodynamics, on the other hand, were not laid until the 18th century when mathematicians such as Leonard Euler and Daniel Bernoulli began to explore the consequences, for a virtually continuous medium like water, of the dynamic principles that Newton had enunciated for systems composed of discrete particles. Their work was continued in the 19th century by several mathematicians and physicists of the first rank, notably G.G. Stokes and William Thomson. By the end of the century explanations had been found for a host of intriguing phenomena having to do with the flow of water through tubes and orifices, the waves that ships moving through water leave behind them, raindrops on windowpanes, and the like. There was still no proper understanding, however, of problems as fundamental as that of water flowing past a fixed obstacle and exerting a drag force upon it; the theory of potential flow, which worked so well in other contexts, yielded results that at relatively high flow rates were grossly at variance with experiment. This problem was not properly understood until 1904, when the German physicist Ludwig Prandtl introduced the concept of the boundary layer. Prandtl's career continued into the period in which the first manned aircraft were developed. Since that time, the flow of air has been of as much interest to physicists and engineers as the flow of water, and hydrodynamics has, as a consequence, become fluid dynamics. The term fluid mechanics embraces both fluid dynamics and the subject still generally referred to as hydrostatics.

One other representative of the 20th century who deserves mention here besides Prandtl is Geoffrey Taylor of England. Taylor remained a classical physicist while most of his contemporaries were turning their attention to the problems of atomic structure and quantum mechanics, and he made several unexpected and important discoveries in the field of fluid mechanics. The richness of fluid mechanics is due in large part to a term in the basic equation of the motion of fluids which is nonlinear - i.e., one that involves the fluid velocity twice over. It is characteristic of systems described by nonlinear equations that under certain conditions they become unstable and begin behaving in ways that seem at first sight to be totally chaotic. In the case of fluids, chaotic behaviour is very common and is called turbulence. Mathematicians have now begun to recognize patterns in chaos that can be analyzed fruitfully, and this development suggests that fluid mechanics will remain a field of active research well into the 21st century.